Fleet managers of over-the-highway trucking enterprises are in constant search for more competitive operational plans. Several fleet managers have chosen to offer leased trucks to operators on a “cost per mile” basis, rather than a flat monthly fee. With the advent of “cost per mile” leasing options, fleet managers are required to ascertain the actual mileage use of a vehicle. Depending on the lease terms and billing schedule, the mileage may need to be determined at times when the truck is a great distance from the fleet main office. Visual odometer readings may not be practical. Even when fleet managers can access the truck to read its odometer, the fleet manager may not have total confidence in the odometer reading.
Under a “cost per mile” lease, operators have a financial incentive to under report mileage. Tampering with existing on-board systems has been a significant problem in some cases and further complicates the task of ascertaining actual mileage. Since the distance measurement devices of a vehicle may be tampered with by a driver operating under a “cost per mile” leasing option, the vehicle odometer measurement is no longer reliable. The odometer is also not a reliable method for the purpose of detecting tampering.
The problem of accurate mileage readings is also relevant with honest operators. A seemingly innocuous change to larger tires can result in a 5% revenue decrease to the fleet operator. Alternatively, a customer using 5% smaller tires will be overcharged. A system in which both a fleet manager and a fair-minded operator can have confidence is needed to further the successful development of programs such as “cost-per-mile” leases.
Several vehicle monitoring systems have been patented that use various distant or speed data to monitor the performance and accuracy of certain vehicle measurement systems. An important consideration when designing these systems is the type of data and source of the data to be used. Some designs have used actual on-board vehicle velocity and distant measurements, while others use mathematically calculated data, or data obtained from satellite systems. Another consideration is whether the system is designed for the purpose of calibrating on-board measurement devices or directed to alternate purposes, such as detecting tampering or unauthorized modifications of the vehicle by the operator.
One prior art proposal teaches using information received from a Global Positioning System, or GPS, receiver to detect failures in a vehicle's speed sensor. A vehicle's initial geographic position is determined by a GPS system. During a predetermined period of time, the vehicle speed as measured by the speed sensor is recorded, and after the period elapses, a second geographic position is recorded. Two distance calculations are performed. The first distance calculation is multiplying the vehicle's speed during the period by the elapsed time. The second distance calculation is calculating the linear distance between the initial and ending GPS geographic positions. If the difference between the two distance measurements falls outside of an allowable tolerance, it is assumed the speed sensor is not functioning properly, or conversely, the positioning system may be malfunctioning. The proposal teaches correcting vehicle speed sensor readings, rather than ensuring accurate odometer readings.
Another prior art proposal teaches monitoring the speed and distance traveled of a vehicle using a Location Determination (LD) system, such as a GPS. An embodiment of the invention uses a LD system to record vehicle locations at periods of low or zero speed over a minimum threshold time, known as a “vehicle arrest event.” The LD system is used to record distance traveled between “vehicle arrest events.” The cumulative distance traveled over any time period can also be obtained, and can be used to calibrate actual odometer readings.
Still another prior art proposal teaches, within a vehicle navigation system, comparing an actual odometer reading with a distance reading obtained from another source, such as a GPS system. An adjustment is performed if the difference between the two readings is more than a threshold level. The adjustment is accomplished by adjusting the pulse rate setting of the vehicle navigation system, so that the distance calculated by the navigational system will match the actual odometer.
Yet another prior art proposal discloses a method for automatically calibrating a displacement sensor in a vehicle. The system ascertains vehicle speed by receiving satellite signal input from a GPS system over a set period of time. The estimated distance traveled over this period is then calculated and compared to signals from the vehicle's displacement sensor which are associated to a distanced traveled. After a series of mathematical calculations are made to determine a correction coefficient, the vehicle's displacement sensor is calibrated.
With the advent of “cost per mile” leasing options offered to truck operators, fleet managers are required to ascertain the actual mileage use of a vehicle. The accuracy of the mileage traveled is important not only for billing purposes, but also to build operator confidence in the “cost-per-mile” leasing operational plan.
Traditional leasing programs also require a leasor to ascertain the actual mileage use of a vehicle. For example, most leasing programs permit a certain amount of use over the term of the lease. Punitive charges are levied for vehicle distance travel over the term limit. These punitive charges provide incentive to some operators to tamper with a vehicle's odometer.
Certain modern truck are equipped with multiple ways to calculate distance travel on-board. For example, a conventional odometer may read distance travel in the instrument cluster, while an engine electronic control unit may calculate mileage as well. The distance readings of the two measurement devices may not coincide if one or more of the methods has been tampered with or is inoperative.
A need in the market exists for a reliable and relatively inexpensive method to accurately record the mileage use of a vehicle while detecting tampering or unauthorized vehicle alterations.